[/
  Copyright 2011 - 2020 John Maddock.
  Copyright 2013 - 2019 Paul A. Bristow.
  Copyright 2013 Christopher Kormanyos.

  Distributed under the Boost Software License, Version 1.0.
  (See accompanying file LICENSE_1_0.txt or copy at
  http://www.boost.org/LICENSE_1_0.txt).
]

[section:primetest Primality Testing]

The library implements a Miller-Rabin test for primality:

   #include <nil/crypto3/multiprecision/miller_rabin.hpp>

   template <class Backend, expression_template_option ExpressionTemplates, class Engine>
   bool miller_rabin_test(const number<Backend, ExpressionTemplates>& n, unsigned trials, Engine& gen);

   template <class Backend, expression_template_option ExpressionTemplates, class Engine>
   bool miller_rabin_test(const number<Backend, ExpressionTemplates>& n, unsigned trials);

These functions perform a Miller-Rabin test for primality, if the result is `false` then /n/ is definitely composite,
while if the result is true then n is probably prime. The probability to declare a composite n as probable prime is
at most 0.25[super trials]. Note that this does not allow a statement about the probability of n being actually
prime (for that, the prior probability would have to be known).  The algorithm used performs some
trial divisions to exclude small prime factors, does one Fermat test to exclude many more composites, and then
uses the Miller-Rabin algorithm straight out of
Knuth Vol 2, which recommends 25 trials for a pretty strong likelihood that /n/ is prime.

The third optional argument is for a Uniform Random Number Generator from Boost.Random.  When not provided the `mt19937`
generator is used.   Note that when producing random primes then you should probably use a different random number generator
to produce candidate prime numbers for testing, than is used internally by `miller_rabin_test` for determining
whether the value is prime.  It also helps of course to seed the generators with some source of randomness.

The following example searches for a prime `p` for which `(p-1)/2` is also probably prime:

[safe_prime]

[endsect] [/section:primetest Primality Testing]
